Facebook’s position as the destination site on the web and the tab you keep open in your browser all day long may have got a little stronger last night when Warner Bros announced last night that it was becoming the first Hollywood Studio to offer its movies for sale or rental via Facebook.

You’ll be able to use Facebook Credits to buy or rent movies, without leaving the Facebook page.

The first film available is Christopher Nolan’s “The Dark Knight.” The cost to rent this blockbuster is 30 Facebook Credits, or $3. You’ll get access to the film for 48 hours, giving you an opportunity to play and pause – and of course still post to Facebook – during the rental period.

Additional titles will be made available over the coming months, but the offer is restricted to consumers within the U.S.

“Facebook has become a daily destination for hundreds of millions of people,” says Thomas Gewecke, President of Warner Bros. Digital Distribution. “Making our films available through Facebook is a natural extension of our digital distribution efforts. It gives consumers a simple, convenient way to access and enjoy our films through the world’s largest social network.”

Facebook isn’t simply the world’s largest social network; it’s one of the largest video sites on the web as well. This should make video distribution an interesting – and likely quite a successful – move on the part of Warner Bros. Here, they sidestep the Hulus and Netflixes and iTunes of the world and deliver films to a large, captive and very social audience.